Models for grinding HSS Lathe Tools

[Glenn Brooks]

Mikey, you might consider making your models with wood blanks. You can even make,them 2x or 3x larger than standard tooling. Our instructor in trade school used large wooden tools for instructional,purposes, and they were very helpful to,see and handle. Regular size works also, and no one can mistake wood for HSS.

Glenn

 

[Rockytime]

Rockytime, just my general purpose square tool will take a 0.050" deep roughing cut in 12L14 on my Sherline lathe as shown below:

View attachment 241311

My tool for mild steel has a bit more side rake and will take 0.060" in a single pass without chattering.

EDIT: I should answer your question as to how I do that. I increase the relief and side rake angles but keep the back rake angle near baseline. This reduces cutting forces significantly while also focusing those cutting forces at the forward area of the side cutting edge. A Sherline lathe is pretty light and cannot handle the cutting forces a standard geometry tool produces but give it a little help with the geometry and it becomes capable of much more. The same is true for all lathes, not just a little Sherline.

Thanks Mikey,
Appreciate the reply and the photo. I am strictly a visual learner. If you can give the angles I can grind it. After over 20 years as a hobby machinist I never did grind proper angles. Since my work is mostly for clock repair and small engine building my tools worked ok. Most used is brass and aluminum but I have a large stash of 12L14. My neighbor had a shop and whenever he ordered steel he would a couple of 12' lengths for me. Over a period of time I ended up with an assortment from 1/4" to 1". Since selling my BP and 12" lathe I only use up to 1/2". Though my projects now are small it would be nice to occasionally take deeper cuts. Very impressed with your belt sander conversion.
Regards, Less

 

[mikey]

a shear tool , acme thread,

Morning Derrick. I actually have never ground a shear tool, although I probably will one day just to see how it works. I have read it works well on 1018 and if it does then it would be worth grinding one because nothing else I know of will finish 1018 nicely.

An Acme thread tool might be something we should discuss at a later time. It isn't something we use every day and I wanted to grind tools that the majority of us might find useful on a daily basis. So far, most of the guys seem to like the idea of tools for the basic lathe operations - facing, turning and threading. What do you think?

 

[mikey]

Mikey, you might consider making your models with wood blanks. You can even make,them 2x or 3x larger than standard tooling. Our instructor in trade school used large wooden tools for instructional,purposes, and they were very helpful to,see and handle. Regular size works also, and no one can mistake wood for HSS.

Glenn

Thanks, Glenn. Yeah, wood would be sooo much easier to grind and I actually considered it. But then I thought is would be better to have a tool that you can set on the tool rest and actually move your hands around to see how you would need to hold the bit to get the right angle to cut a particular face. That is what I think is hard for guys to visualize. My hope is that if I tell them how I ground that particular feature and they can match what I'm saying in real time, with the tool on the rest, then it might just click.

I also wanted to show them tools that I know, without a doubt, will cut as intended. If I were giving a class on this subject, for sure a wooden model would be far more useful.

Thanks for the suggestion, Glenn!

 

[dlane]

Yup just the basic turning tools for everyday turning should be helpful for many people.

 

[mikey]

Thanks Mikey,
Appreciate the reply and the photo. I am strictly a visual learner. If you can give the angles I can grind it. After over 20 years as a hobby machinist I never did grind proper angles. Since my work is mostly for clock repair and small engine building my tools worked ok. Most used is brass and aluminum but I have a large stash of 12L14. My neighbor had a shop and whenever he ordered steel he would a couple of 12' lengths for me. Over a period of time I ended up with an assortment from 1/4" to 1". Since selling my BP and 12" lathe I only use up to 1/2". Though my projects now are small it would be nice to occasionally take deeper cuts. Very impressed with your belt sander conversion.
Regards, Less

Good Morning, Less. I had a chuckle about the tool angles - who knows what proper angles are? We use what works for us, right? Still, I can tell you how I grind tools for mild steel, brass and aluminum and you can give them a try to see if it improves your current tool's performance. All tools have a general purpose shape.

• Mild steel: 15 degree of side and end relief, 18 degrees side rake, 12-15 degrees of back rake. The back rake depends on where I want the cutting forces concentrated; less angle focuses the forces more toward the side cutting edge so it roughs better, more angle focuses them at the tip so it finishes better. The back rake is sufficient to augment side rake for efficient chip clearance in either case. Note that the relief angles are only moderately increased, while side rake is more than a mild steel tool will normally have; this is to reduce cutting forces primarily and cutting temps secondarily. This tool will take a 0.060" deep roughing cut on a little Sherline lathe. The lathe will moan but it won't groan or chatter, which is exactly what we should see when the lathe is used at max capacity. This same tool, when used on your Maximat 7, will walk through the same cut in mild steel without even slowing it down.
• Brass: Side and end relief of 15 - 17 degrees, zero side and back rake. I have found that brass likes fairly large relief angles. I've gone up to 20 degrees of relief but found that the edge started to wear a bit too fast - brass is hard! I've also tried some rake on these tools and while 5 degrees of side rake seems to help a little, it isn't enough to spend the time to grind it. I do hone my brass tools often; sharp is good for brass. This tool will easily take a 0.050" deep cut on a Sherline lathe in brass. I tend to use smaller nose radii for my brass tools. I know that most guys use a large nose radius to improve the finish but I find 1/32 more than adequate for my needs.
• Aluminum: Side and end relief = 15 degrees, side rake 18 degrees, back rake 40 degrees. Yeah, I know, 40 degrees of back rake! This produces a very positive rake cutter that will take a 0.100" deep cut in 6061-T6 on a Sherline lathe. Of course, very few of us waste material like that but it will make the cut. It will also give superb finishes because the back rake focuses all the cutting forces at the tip; all you need is a nose radius of 1/64 to 1/32" and it will produce a near mirror finish with a roughing cut and a mirror finish with a sizing cut and lubricant. I also find the back rake reduces or eliminates a built up edge; the chip is moving so fast and with so little heat that it just doesn't stick as long as I use some WD-40 on it. Give it a try and watch the chip flow right off the tip of the cutter.

I use 3/8" bits and use the same cutters on my Sherline and my Emco Super 11. They work well on either lathe. The mild steel and aluminum bits will easily take a 0.250" depth of cut on my 11" lathe and while I know they can go deeper, I don't need to waste material to find out how much deeper they will go.

Play with your lead angle with these cutters; there is a sweet spot for turning, roughing, finishing and facing.

I hope this helps, Less. It is always difficult to give hard numbers for things like a cutting tool. Wear, tool posts, usage differs from user to user but I hope these tools work as well for you.

Oh, and thanks for the compliment re the belt sander!

 

[mikey]

Okay, it sounds like we seem to agree that basic tools for lathe operations will work for most folks - a general purpose tool for turning/facing, a knife tool for facing and thin work and a standard 60 degree threading tool. For the general purpose tool, I am going to grind my Square Tool because it just works for most stuff we turn; you can easily modify the angles if that better suits your needs.

I have the keystock in hand and have ordered some new belts so I'm ready to go. Now I need a volunteer to handle the distribution of these models. There will be three sets and there seems to be more than three guys who want to see them. Our volunteer would compile and track a list of folks to make sure nobody is missed and that the sets move along on a timely basis. I should think a week or two is enough for each guy; what do you think? So, if we can find a volunteer coordinator, everyone who wants to look at these things can PM him and he will keep track of things. As the maker, I would like to choose who gets the sets first.

Anybody willing to step up?

 

[Aukai]

I do not have any blanks, or a lathe in hand, and will not be first on the list for sure. A PM list might get bulky, but doable. Another thread where the list can be discussed about who has the samples, and would be a head count. Then PM the address to who currently has it for next in line. Not sure how choosing where it goes next would be done. Thinking out loud.

 

[Rockytime]

Good Morning, Less. I had a chuckle about the tool angles - who knows what proper angles are? We use what works for us, right? Still, I can tell you how I grind tools for mild steel, brass and aluminum and you can give them a try to see if it improves your current tool's performance. All tools have a general purpose shape.

Hi Mikey, WOW! Great dissertation! I am surprised at the severe angles. I printed it and am posting it in my shop. I use 1/4" on the Sherline and 3/8" on the seven inch. Gonna have fun trying these. BTW I covet your 11". I have a couple of friends with the MaxiMat11. Dynamite lathe. My 7" has the mid bed milling column but I don't use it as it is inconvenient. Again thank you so very much for your Information.
Regards, Les

 

[Z2V]

Hi Mike
If you are going to the trouble to make the tools I'd be more that happy to help if needed.
Im very new to hobby machining and tool grinding so I'll take all the guidance I can get. Absolutely no offense taken.